[Bug 1896229] Re: systemd-networkd thinks it loses its lease every renewal

[Shaun Crampton]

** Attachment added: "PCAP of DHCP traffic"
   https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1896229/+attachment/5412183/+files/dhcp.pcap

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to systemd in Ubuntu.
https://bugs.launchpad.net/bugs/1896229

Title:
  systemd-networkd thinks it loses its lease every renewal

Status in systemd package in Ubuntu:
  New

Bug description:
  With a server running 20.04 on AWS, I noticed connectivity glitches
  once per half hour.  Eventually managed to correlate it with DHCP
  renewals.  Each time systemd-networkd does a renewal, it logs that the
  lease was lost and goes through a cycle of removing and re-adding the
  IP and routes (Even though it's the same IP and routes).  This causes
  disruption, especially to SNATted flows; if a packet arrives for an
  SNATted flow during hte windows where the IP is removed then (I think)
  the host sends a RST and the flow gets torn down.  (In any case, such
  flows get lost during the glitch.)

  I'd expect a DHCP renewal to be completely transparent; the IP
  shouldn't flap, it should just be updated to have a longer lifetime.

  I managed to capture a PCAP of the DHCP renewals along with a debug
  log from systemd-networkd.

  ProblemType: Bug
  DistroRelease: Ubuntu 19.10
  Package: systemd 242-7ubuntu3.11
  ProcVersionSignature: User Name 5.3.0-1030.32-aws 5.3.18
  Uname: Linux 5.3.0-1030-aws x86_64
  ApportVersion: 2.20.11-0ubuntu8.9
  Architecture: amd64
  Date: Fri Sep 18 13:05:22 2020
  Ec2AMI: ami-0d3d788094d3f0aa9
  Ec2AMIManifest: (unknown)
  Ec2AvailabilityZone: us-west-2a
  Ec2InstanceType: t3.large
  Ec2Kernel: unavailable
  Ec2Ramdisk: unavailable
  Lsusb: Error: command ['lsusb'] failed with exit code 1:
  MachineType: Amazon EC2 t3.large
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=C.UTF-8
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-1030-aws root=PARTUUID=e96a8035-01 ro console=tty1 console=ttyS0 nvme_core.io_timeout=4294967295 panic=-1
  SourcePackage: systemd
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 10/16/2017
  dmi.bios.vendor: Amazon EC2
  dmi.bios.version: 1.0
  dmi.board.asset.tag: i-0fc0b0107c428fe19
  dmi.board.vendor: Amazon EC2
  dmi.chassis.asset.tag: Amazon EC2
  dmi.chassis.type: 1
  dmi.chassis.vendor: Amazon EC2
  dmi.modalias: dmi:bvnAmazonEC2:bvr1.0:bd10/16/2017:svnAmazonEC2:pnt3.large:pvr:rvnAmazonEC2:rn:rvr:cvnAmazonEC2:ct1:cvr:
  dmi.product.name: t3.large
  dmi.sys.vendor: Amazon EC2

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1896229/+subscriptions